1. Field of the Invention
The present invention relates generally to a closed compressor and, in particular but not exclusively, to a closed compressor for use in, for example, an automobile air conditioner. The present invention also relates to a method of assembling such compressor.
2. Description of the Related Art
Conventionally, open compressors are generally used for air conditioners in engine-driven automobiles, while closed compressors (motor-driven compressors) that are employed in household air conditioners are generally used for air conditioners in electric cars.
FIG. 6 depicts a horizontal scroll compressor for use in a conventional household air conditioner. The compressor shown therein includes a compression mechanism 4 and a motor drive section 6 for driving the compression mechanism 4, both of which are contained in a closed vessel 2. The compression mechanism 4 includes a stationary scroll 4a fixedly mounted in the closed vessel 2, and an orbiting scroll 4b held in engagement with the stationary scroll 4a to undergo an orbiting motion relative thereto. The motor drive section 6 includes a stator 6a fixedly mounted in the closed vessel 2, and a rotor 6b for orbiting the orbiting scroll 4b relative to the stationary scroll 4a.
The orbiting scroll 4b has a shaft 4c integrally formed therewith so as to extend rearwardly therefrom. The shaft 4c is loosely inserted into an eccentric bearing 10 mounted on one end of a crankshaft 8, on an intermediate portion of which the rotor 6b is securely mounted. The one end of the crankshaft 8 is rotatably supported by a main bearing 12, which is held by a bearing support 14. The other end of the crankshaft 8 is similarly rotatably supported by an auxiliary bearing 18, which is held by a bearing support 16. Both the bearing Supports 14 and 16 are fixedly mounted in the closed vessel 2.
In assembling the scroll compressor of the above-described construction, the stationary scroll 4a is first held in engagement with the orbiting scroll 4b so as to allow the orbiting motion of the orbiting scroll 4b relative to the stationary scroll 4a. The stationary scroll 4a is then fixed on the bearing support 14 by means of a plurality of bolts, thus constituting the compression mechanism 4. Furthermore, the rotor 6b is shrink-fitted to the crankshaft 8, while a generally cylindrical shell 2a of the closed vessel 2 is shrink-fitted to the stator 6a.
Thereafter, the bearing support 16 on which the auxiliary bearing 18 is held is welded to the generally cylindrical shell 2a, and the crankshaft 8 to which the rotor 6b has been shrink-fitted is inserted into the stator 6a so that the compression mechanism 4 may be placed at a predetermined position in the proximity of an open end of the generally cylindrical shell 2a. The bearing support 14 is then welded to the generally cylindrical shell 2a through a plurality of openings (not shown) formed in the generally cylindrical shell 2a. Finally, a pair of side shells 2b, 2c are welded to the generally cylindrical shell 2a, thereby completing the assembling work.
In the case of the scroll compressor assembled in the above-described manner, the stationary scroll 4a constituting the compression mechanism 4 and the bearing support 14 are both made of iron-based material and, hence, they have a great influence on the weight of the compressor. However, the weight requirement (weight-saving) on the compressors for household air conditioner is not so strong as that on the compressors for automobiles.
Recently, there is an increasing demand for environmental protection or energy saving, and automobiles of lighter weight are also demanded. Particularly, as far as electric cars are concerned, the lighter weight is one of the most important problems, because the electric cars are inferior in driving force to gasoline-driven cars.
In view of the need for lighter weight, it is conceivable that the component parts of the compression mechanism be changed from iron-based material to aluminum or aluminum-based material. In that case, however, if conventional gas welding is employed to fix the compression mechanism to the generally cylindrical shell, there arises a problem in that the aluminum-based material is fused and, hence, joining is not possible.